Mineral oil extended polyurethane system containing a coupling agent for decontaminating and sealing the interior spaces of an insulated electrical device

ABSTRACT

This invention provides a method of sealing and purging contaminants from the internal free spaces of an insulated electrical device by forcing into said free spaces a low viscosity material that acts to displace fluid contaminants from within said free spaces. The material later cures in situ to form a hydrophobic seal with good electrical properties. Also disclosed herein is a method for rehabilitating waterlogged plastic insulated multiconductor communications cables of the type employed in telephone systems.

This application is a continuation-in-part of our patent applicationSer. No. 432,479 filed on Jan. 11, 1974 and now abandoned.

This invention relates to a method of rehabilitating insulatedelectrical devices that have been contaminated by fluid penetration oftheir interior free spaces. More specifically, the invention concerns amethod for displacing aqueous fluid penetrants from the interior freespaces of an insulated electrical apparatus and sealing the purgedspaces against further aqueous fluid penetration while maintaining theelectrical properties of the apparatus.

Water penetration of insulated electrical devices and especially plasticinsulated multiconductor telephone cables can seriously effect theelectrical properties of such structures. The problem of waterpenetration is amplified when the electrical device is positionedunderground or in a high humidity environment. In the case of atelephone cable, water penetration can seriously impair the electricaland mechanical .[.improperties.]. .Iadd.properties .Iaddend.that arecritical to its continued operation. The pressure of water betweeninsulated conductors can cause a significant increase in theircapacitance and can lead to the development of electrical leakagepathways between conductors having pinhole insulation defects. Leakageof water into the unoccupied spaces between the insulated cable pairsand the outer sheath can also cause a significant increase in signalattenuation, noise, and lead to conductor corrosion.

Replacement of waterlogged cables is not a satisfactory solution to theproblem of water contamination in most cases because of the expense andinconvenience involved in such an undertaking. However, in order tomaintain suitable operating parameters the cable must be rehabilitatedby removal of the fluid contaminant and restoration of the electricaland mechanical conditions that render it useful as a means fortransmission of telephone signals.

The prior art has advanced several methods of eliminating aqueouspenetrants from the interior free spaces of plastic insulated conductorcables. One technique involves the use of acetone to eliminate water.Removal of water, alone, is not sufficient in most cases since the meansfor water penetration is not eliminated and unless a continuous supplyof acetone is maintained in the cable, renewed fluid penetration can beexpected to occur. Another method of purging water contaminants dependsupon pumping a gas into the interior free spaces of the cable via acoupling to the outer cable sheath and maintaining a continuous elevatedgas pressure between interconnected cable segments. This method isimpractical for use in most cases since it requires the continuedoperation of a gas generating source in order to prevent subsequentwater penetration.

A recently developed technique removes water that has penetrated intothe interior free spaces of a telephone cable by pumping a hydrophobicinsulating material into the cable. The insulating material isintroduced at low viscosity and cures in place to a high viscosity thusprecluding its escape via defects in the outer covering of the cable.The cured material simultaneously acts as a hydrophobic barrier tosubsequent water penetration. This system employs a cross-linkingcomposition which is a solution of a liquid urethane elastomer in anaromatic oil. A principal disadvantage of this system is that after thereclamation agent has cured in place, the aromatic hydrocarbon oil canescape from the cross-linked system and severely attack the plasticconductor connectors, or polyolefin sheathing.

In addition to the water elimination, low viscosity, and barrierproperties previously set forth a rehabilitation material for use insealed electrical devices must fulfill other critical requirements. Itmust be compatible with plastic connectors (such as polycarbonates),normally employed in joining lengths of telephone cable..[.compatibility.]. .Iadd.Compatibility .Iaddend.with polyolefins isimportant and an effective rehabilitation agent should not stress crackthese materials which frequently form the insulating sheath of telephonecables. The agent should also have good mechanical properties,relatively long life expectancy and a relatively flat viscosity-timecurve to insure good pumpability and to enable longer cable segments tobe rehabilitated and filled in a single application.

It is also important that a cable rehabilitation agent display superiorelectrical characteristics such as high insulation resistance, volumeresistivity dissipation factor and low dielectric constants since inmost cases it must rehabilitate the cable with respect to theseproperties. Additionally, the reclamation agent should have a lowspecific gravity in order to impart a minimal weight gain to herehabilitated cable and less water and air entrapment which can resultfrom the turbulence effects of pumping into a confined cable space.Also, the rehabilitation compound should not attack polyethyleneterephthalate or other synthetic polymer materials employed in cableconstruction.

Finally, current health and safety regulations make it imperative that arehabilitation agent be relatively non-toxic, non-volatile and easy tohandle in the field.

It is therefore an object of this invention to provide a method ofeliminating water that has penetrated the interior free spaces of aninsulated electrical apparatus and to simultaneously provide a barrierto prevent subsequent water penetration.

Another object of the invention is to rehabilitate the electricalproperties of an insulated electrical apparatus that has becomewaterlogged.

A further aspect of the invention is to dislodge aqueous contaminantsfrom the interior free spaces of a plastic insulated multiconductortelephone cable by introduction of a cable rehabilitation compound under.[.pressue.]. .Iadd.pressure .Iaddend.over lengthy cable spans in asingle operation.

Another aspect of this invention is the provision of a low viscosityagent capable of eliminating aqueous contaminants from the interior freespaces of an insulated electrical cable and which cures in situ toprovide a permanent barrier to subsequent water penetration.

These and other objects of the instant invention will be betterunderstood by reference to the following specification and theaccompanying drawing wherein:

FIG. 1 is a front elevational view, partly in section, of a length ofplastic insulated multi-conductor telephone cable.

The generic aspect of the instant invention involves a method ofeliminating water that has penetrated the interior free spaces of aninsulated electrical apparatus by forcing into the free spaces of theapparatus a rehabilitation agent comprising a low viscosity solution ofurethane precursors that are extended in a mineral oil. Therehabilitation agent is introduced into the apparatus at very lowviscosity by pumping. Continuous introduction of the low viscosity agentis maintained in order to drive it along the length of the free spacesthroughout the electrical apparatus. The rehabilitation compoundinitially displaces aqueous contaminants, such as water, that havepenetrated into the interior free spaces between the differentcomponents of the insulated device. Thereafter, the low viscosity agentcures in situ to form a gel-like urethane structure in which the mineraloil is retained. In this manner, water contaminants are removed from theinsulated electrical arrangement, a barrier is formed against furtherwater penetration and the electrical properties of the device arerestored. This technique is especially useful in the rehabilitation ofplastic insulated conductor cables.

A specific embodiment of this invention employs a two-component urethanecable rehabilitation agent extended with a mineral oil. Polyurethanes,being very polar elastomers, were heretofore thought to be almostcompletely incompatible with the non-polar minerals oils and extensionof urethanes was traditionally accomplished with aromatic oils. Althoughthe prior art has been able to achieve some extension of polyurethanesusing mineral oils, these efforts have been limited to relatively lowextension ratios of about 2:1, oil to polymer. At higher extensionratios these prior art systems begin to lose their oil contents byexudation (or spewing) shortly after cure. We have found that thecoupler is necessary in our systems .[.which comprises castor oil,polyether polyols in combination with hydroxyl bearing polybutadiene anda diisocyanate.]. to obtain stable non-spewing elastomeric materialswith extensions even as low as 1:1 and up to 10:1 if desired. Withoutthe coupler the elastomer spews oil.

For purposes of this specification, mineral oils are considered to bethose aliphatic, cycloaliphatic, and branched aliphatic saturatedhydrocarbons that contain from 15-20 C atoms and are distilled frompetroluem. Included in this classification are naphthenic and paraffinoils. Paraffin oils are the preferred mineral oil for use in thisinvention. In the instant invention it was unexpectedly found that across-linkable low viscosity solution of a mineral oil, a preselectedpolyol and a preselected isocyanate prepolymer, in which either theprepolymer or the polyol constituent contain a polybutadiene moiety canbe prepared through the use of liquid coupling agents that arepreferably high boiling esters of organic diacids or diols. Morespecifically the coupling agents may be saturated or unsaturated,(preferably .[.unsaturated.]. .Iadd.saturated.Iaddend.)aromatic-aliphatic, cyclo-aliphatic or wholly aliphatic esters, such as2,2,4-trimethyl 1,3-pentane diole diisobutyrate. Other suitable liquidcoupling agents include those in which a polar group is attached to analkane structure, such as, for example, tributyl phosphate.

In order to effectively compatibilize the mineral oil with across-linking urethane elastomer, it has been discovered that a couplermust satisfy several criteria. Firstly, it must be soluble in mineraloils in all proportions. In other words, the coupler should be misciblein all proportions with mineral oils to form a true solution (i.e., onepart coupler/99 parts mineral oil or 99 parts coupler/one part mineraloil). It has also been found that coupler compounds suitable for use inthis invention have a solubility parameter (δ) in the range of 7.0-9.5and a hydrogen bond index number within the range 6 to 12.

The (δ) value of a substance is calculated according to the formula

    δ=(ΔE/V).sup.1/2

where ΔE is the energy of vaporization to a gas at zero pressure (i.e.,an infinite separation of the molecules); and

V is the molar volume of component present. The dimensions of δ are(calories per cubic centimeter)^(1/2). Since it is possible to ascertainΔE and V for most substances, the value of the solubility parameter or δmay be calculated from the heat of varporization ΔH, since it can beshown that

    .[.ΔE.sub.25° C. =ΔH.sub.25° C. -592.]. .Iadd.ΔE.sub.25°C. =ΔH.sub.25°C. -592 .Iaddend.

Since the value of ΔH at 25° C. for most compounds may be found in theliterature, this value may be used to calculate ΔE and then δ. Furtherdetails on solubility parameters and means for their calculation arefound in an article entitled Solubility Parmeter Values by H. Burrelland B. Immergut at P.IV-341, of Polymer Handbook edited by J. Brandrupand E. H. Immergut, 3rd Edition Interscience Publ., June 1967.

It has also been determined that the coupling agents of this inventionhave a hydrogen bond index in the range 6.0-12.0. The hydrogen bondingindex number (γ) of a compound is a measurement of its proton (hydrogen)attracting power. The hydrogen bond index number (γ) (proton attractingpower) of a compound is measured by comparing the relative strengths ofthe hydrogen bonds which the liquid compounds forms with a common protonor Deuterium donor.

In practice, this is done by dissolving deuterated methanol in theliquid to be tested. The proton attracting power of a liquid compound isdetermined by measurement of the movement produced on the OD vibrationalband of CH₃ OD. The OD vibrational band occurs at 4μ in the liquid CH₃OD and at 3.73μ in the monomolecular CH₃ OD in dilute benzene solution.Benzene is considered to have an OD vibrational shift of 0. Theformation of hydrogen bonds shifts the monomolecular band to lowerfrequencies or longer wavelengths. The stronger the proton attractingpower of a liquid, the greater is the shift which it produces on the ODband. By Infrared Spectroscopy the perturbations of the OD band can beestablished.

The γ value of a compound may be determined by measuring the shift inwave numbers of the OD vibrational band after .[.disolution.]..Iadd.dissolution .Iaddend.in the liquid compound and dividing theresulting number by 10. (Wave number is the reciprocal of an angstromunit). Those compounds having a γ number of 0 to 6.0 are generallyacknowledged to be weak hydrogen bond acceptors. Compounds having indexnumbers in the range of 6.0 to 12.0 are usually considered moderatehydrogen bond formers and those having index numbers above 12.0 areconsidered to be strong hydrogen bonders. The liquid coupler compoundsuseful in this invention are those having a hydrogen bond index number(γ) falling in the range between 6.0 and 12.0 as determined by theabovementioned technique. The origin of the Hydrogen Bond index systemand additional details on the means for its computation are found in aseries of articles by W. J. Gordy in J. Chem. Physics, Vol. VII, pp.93-99, 1939, Vol. VIII, pp. 170-177, 1940 and Vol. IX, pp. 204-214,1941.

Coupler compounds are selected to be non-reactive with thecross-linkable urethane elastomer composition and accordingly do notcontain any labile hydrogen atoms in their structure.

As indicated above, it is important that the viscosity of the solvent,coupler and polymer solution be kept to a minimum in order to effecttheir introduction into the free spaces of a cable that is to bereclaimed. However, the amount of polymer in the rehabilitationcomposition should also be minimized to the greatest extent possible inorder to prevent excessive weight gain in the apparatus to berehabilitated as well as for reasons of economy.

In order to provide suitable mechanical and electrical properties forreclamation of insulated electrical devices, within a reasonable periodof time at ambient temperature, the gelled paraffinic oil extendedelastomer system should be cross-linked. Cross linking is obtained byuse of either an isocyanate or a polyol, more usually a polyol having afunctionality of between 2.0 and 3.0, and preferably 2.2-2.7. Also, thevolume resistivity of the paraffin extended polyurethane as determinedby ASTM D-257 should be at least 2.5×10¹⁰ ohm-cm and preferably higher.

The instant mineral oil extended rehabilitation compounds are preferablyprepared on the site by admixing the contents of two separatecontainers. In this manner instruction of personnel in the formulationand use of the rehabilitation material is facilitated because thecontents of the two containers are preferably mixed in approximatelyequal proportions just prior to their introduction into the apparatus tobe reclaimed. If necessary, all the individual ingredients can beadmixed together on the site.

In one container is an isocyanate terminated prepolymer, preferably inmineral oil solution. Between about 50 and 200, and preferably about 100grams of isocyanate prepolymer is employed per liter of solution in thefirst container. The prepolymer is preferably formed from acycloaliphatic diisocyanate such as, for example, 3-isocyanato methyl,3,5,5-trimethylcyclohexy isocyanate (IPDI). The useable isocyanates formaking the prepolymers in this invention also include the aliphatic andaromatic diisocyanates such as tolylene diisocyanate (TDI),4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate,phenylene diisocyanates, or mixtures of these materials, 4,4'-methylenebis(cyclohexyl isocyanate) and hexamethylene diisocyanate, as well asrelated aromatic and aliphatic isocyanates, which may also besubstituted with other organic or inorganic groups that do not adverselyaffect the course of the chain-extending and/or cross-linking reaction.

Formation of the isocyanate terminated prepolymer is accomplished byreacting an excess-of one of the preceding isocyanate components with apolyol having a relatively high molecular weight of between about 1,000and 6,000. Among the polyols useful in formation of the isocyanateterminated prepolymer are those selected from compounds basedessentially on polybutadiene, castor oil or hydroxyl bearing polyethersor conbinations of them.

Suitable polyether polyols include aliphatic alkylene glycol polymersexemplified by polypropylene ether glycol and poly 1-4 butylene etherglycol. Also trifunctional compounds exemplified by the reaction productof trimethylol propane and propylene oxide may be employed as the polyolconstituents.

The polybutadiene based polyols are liquids that are founded on hydroxylterminated liquid butadiene homopolymers and hydroxyl terminatedbutadiene copolymers with styrene. A typical butadiene based polyolcopolymer has the approximate structure ##STR1## wherein X is C₆ H₅ fora styrene-butadiene copolymer and

a=0.75

b=0.25 and n=57-65

A butadiene homopolymer useful in preparing the isocyanate terminatedprepolymers of the invention has the structure ##STR2## wherein n=57-65

This class of liquid hydroxy bearing polybutadiene polymers areavailable from Arco Chemical Company under the trademark POLY-BD.

Properties of the hydroxyl-terminated polybutadienestyrene copolymersare

Butadiene, Wt. %=75

Styrene, Wt. %=25

Viscosity, poise at 30° C.=225

OH content meg./gm=0.65

Moisture--Wt. %=0.05

Iodine Number=335

The prepolymer is preferably formed from the reaction of an excess ofIPDI and the above-mentioned hydroxyl terminated homopolymer ofpolybutadiene and has a hydroxyl functionality of 2.2-2.4 and anequivalent weight of approximately 1260. Another prepolymer formulationthat has been found especially useful in preparing mineral oil extendedcable rehabilitation agents is formed by reacting an excess of toluenediisocyanate with castor oil or a hydroxyl terminated polybutadienehomopolymer or a polyether (such as poly(oxypropylene) glycol of.[.polytetramethylene glycol.]. .Iadd.polytetramethyl etherglycol.Iaddend.. The preferred castor oil composition for use inpreparation of this prepolymer and generally in this invention comprisesa mixture of about 70% pure glyceryl triricinoleate and about 30%glyceryl diricinoleatemonooleate or monolinoleate and is available fromBaker Castor Oil, Bayonne, New Jersey, as "DB oil".

In the second container is a solution of between about 75 and 200 andpreferably about 150 grams per liter of a preselected polyol in mineraloil. Suitable polyols with which the polyisocyanate prepolymers in thefirst container may be reacted include castor oil, polyethers such as.[.poly tetramethylene glycol.]. .Iadd.polytetramethylene ether glycol.Iaddend.homopolymers or copolymers of hydroxy .[.,.]. bearingbutadiene, poly (oxypropylene) glycol or combinations of them.

The mineral oil component may be admixed with either or both of theprepolymer or polyol stages as long as a sufficient amount of the liquidcoupler agent is present to compatibilize the mineral component with therespective stage.

The molecular weight (mw.) of the polyols used in this second part ofthe system should fall between about 1000 and 6000 and preferably in therange 2,000-4,000. The molecular weight of the polyols used to form theprepolymer also lies within the same range. Preferably, the polyolreactant is a hydroxyl bearing polymer of either repeating butadienemonomer units or a copolymer of butadiene and styrene. In fact, it hasbeen determined that in order to secure effective operation andcompatability of a mineral oil in a urethane elastomer system, eitherthe polyisocyanate prepolymer or the polyol must include a polybutadienemoiety as part of their structure. While it is not important whether thepolybutadiene moiety is present in the prepolymer portion or the polyolprecursor of the polyurethane system, it has been determined that fullcompatibility of the mineral oil polyurethane system (especially inhighly extended systems) is not obtained absent the presence of thebutadiene moiety in the polyurethane structure.

The mineral oil extended polyurethane is deemed to be a compatiblesystem since either or both of the prepolymer or the polyol canaccommodate the mineral oil and go on to form a polyurethane polymerthat cures to a gel but does not exude the extender oil after cure.Accordingly, compatibilizing refers to the ability of the curedpolyurethane system to retain the mineral extender oil within itsstructure while remaining in a gel-like consistency. Once the oil hasbeen compatibilized with the polyurethane structure it is not lost byspewing or exudation after cure. Determination as to the proper amountof coupler for use in compatibilizing a given quantity of mineral oilwih a specific prepolymer or polyol formulation is best done byexperimentation, although it has been determined that the completedurethane elastomer system should contain about 8 to about 20 andpreferably between about 121/2 and 15 parts by weight of polymer solids,between 60 and 75 and preferably between 65 and 70 parts by weightmineral oil and between about 10 and 25 preferably between about 15 and20 parts by weight of coupler. In one preferred embodiment a hydroxybearing homopolymer of butadiene is reacted with an excess of3-isocyanatomethyl 3,5,5 trimethylcyclohexyl isocyanate in the presenceof 2,2,4-trimethyl 1,3, pentanediol diisobutyrate coupling agent to forma prepolymer which is in turn diluted in mineral oil and an additionalamount of coupler. The dilute prepolymer solution is then reacted with adilute solution of the hydroxy bearing butadiene homopolymer in mineraloil and the same liquid coupling agent to yield an elastomer systemhaving the following make-up:

(Polymer) Solids 15 parts by weight

(Extender oil) Paraffin 64 parts by weight

Coupler 20 parts by weight

Catalyst 1 part by weight

The composition ranges cited above cover the preparation of highly oilextended polyurethanes possessing gel-like consistencies. However, thisinvention also covers the preparation of lower oil extended polyurethaneelastomers. The broad ranges therefore contemplated by the instantinvention covering both types of products comprise from about 8 to about45 parts by weight of polymer solids, from about 25 to about 75 parts byweight of mineral oil and from about 10 to about 35 parts by weight ofcoupler.

For the lower oil extended polyurethanes contemplated by the instantinvention which are useful for casting systems for a variety of pottingand encapsulating applications the ranges should comprise from about 20to about 25 parts by weight of polymer solids, from about 25 to about 60parts by weight of mineral oil and from about 25 to about 35 parts byweight of coupler.

The liquid couplers employed to compatibilize mineral oils with theinstant polyurethane systems and to secure both high and low oil/polymerextension ratios according to this invention are selected according tothe previously enumerated criteria. Generally, the initial criteria isthat the coupler liquid must be soluble in mineral oils in allproportions to form a true solution.

The coupler compounds will also possess a solubility parameter (δ)between 7.0 and 9.5 preferably in the range between 7.2 and 9.5.

Final evaluation of a coupling agent is usually made with reference toits hydrogen bonding index (γ) the preferred coupling agents havinghydrogen bonding index numbers in the range 8.2 to 8.8 as determined bythe procedures previously set forth. In the screening of potentialcoupling agents as determination as to solubility parameter and hydrogenbonding index number can be made using well-known analytical techniques.The solubility parameter value (δ) and hydrogen bonding index number (γ)are available in the literature for many compounds and may be determinedby reference to the appropriate text.

From the chemical standpoint, the couplers are liquids and preferablyesters of organic diacids or diols that boil at temperatures in excessof 220° F. Other suitable coupling agents include those liquids in whicha polar group is attached to an alkane structure such as, for example,tributyl phosphate. The liquid coupling agents may be saturated andunsaturated (although they are preferably saturated) and may bearomatic-aliphatic, cyclo-aliphatic, or wholly aliphatic esters, such asfor example 2,2,4-trimethyl 1,3 pentanediol diisobutyrate.

The preferred couplers for use in this invention are selected fromamount di-2-ethylhexyl .[.sebecate,.]. .Iadd.sebacate, .Iaddend.acetyltributyl citrate, di-2-ethylhexyl adipate, dioctyl adipate, dibutylfumarate, di-n-butyl .[.sebecate and.]. .Iadd.sebacate,.Iaddend.di-2-ethylhexyl citrate and acetyl di-2-ethylhexyl citrate.Especially good results are obtained when2,2,4-trimethyl-1-3-pentanediol diisobutyrate is employed as thecoupling agent. A list of the principal coupling agents that have thusfar, been found useful in this invention is set forth in Table A:

                  TABLE A                                                         ______________________________________                                        COUPLERS                                                                                                 (δ)                                                                     (Cal/                                                Chemical Name            per CC)                                            ______________________________________                                        .Iadd. 1. 2,2,4 Trimethyl-1,3.Iaddend..[. 1. 2,2,4 Trimethyl-1-1,3.].           Pentanediol Diisobutyrate                                                                              8.2                                                 2. Di-2-ethylhexyl.Iadd.sebacate.Iaddend..[.sebecate.].                                                 8.6                                                 3. Acetyl Tributyl Citrate                                                                              9.2                                                 4. Di-2-ethylhexyl Adipate                                                                              8.7                                                 5. Diisodecyl Phthalate   7.2                                                 6. Dioctyl Adipate        8.7                                                 7. Tributyl .[.Phoshate.]..Iadd.Phosphate.Iaddend.                                                      8.6                                                 8. Dibutyl Fumarate       8.5                                                 9. .[.Acetyl Tri-2-ethylhexyl.]..Iadd.Acetyl Di-2-ethylhexyl.Iaddend.          Citrate                  8.6                                                10. Di-n-butyl .[.Sebecate.]..Iadd.Sebacate.Iaddend.                                                     8.8                                                11. Dioctyl Phthalate      8.8                                                12. Di-2-ethylhexyl .[.citrate.]..Iadd.Citrate.Iaddend.                                                  8.6                                                13. Isobutyl Acetate       8.4                                                14. Methyl ethyl Ketone    9.5                                                15. Methyl-n Butyl Ketone  8.6                                                ______________________________________                                    

Selection of a particular coupler determination of the correct amount tobe employed is determined by experimentation and will vary from oneurethane system to another. The selection is dependent upon chemical andphysical differences in various prepolymers and polyols as well as uponthe desired amount of mineral oil extension in the cured system.

The couplers of this invention enable paraffin oil extensions of up toabout 950% (by weight) based upon polyurethanes, formulated frompolyether diols and triols, castor oil, as well as polybutadiene polyolsand combinations of these. These mineral oil extended urethane elastomersystems display dielectric constants of 3.4 at 1KHz (as determined byASTM D-150) or lower. Examples .[.I-XII.]. .Iadd.I-XIII.Iaddend.illustrate the preparation of mineral oil extended urethaneelastomers for use in rehabilitating insulated electrical devices. TableB outlines the functionality and molecular weights of the polyolsemployed in Examples .[.I-XII..]. .Iadd.I-XIII. .Iaddend.

                                      TABLE B                                     __________________________________________________________________________     Polyol                         OH Functionality                                                                       MW                                   __________________________________________________________________________    1. .Iadd.Polybutadiene.Iaddend..[.Polybudadiene.].                                                            2.3-2.4  2912-3038                            2. Styrene polybutadiene                                                       copolymer                      2.0      3280                                 3. Castor oil                   2.7       923                                 4. Polypropylene/glycol         2.0      2040                                 5. Trimethylolpropane                                                          propylene oxide adduct         3.0      4145                                 6. .Iadd.Polytetramethylene Ether Glycol.Iaddend..[.Polytetramethylene        Glycol.].                       2.0      2004                                 __________________________________________________________________________

Table C contains a summary of the important physical and chemicalproperties of the Prepolymer components of Examples .[.I-XII..]..Iadd.I-XIII. .Iaddend.(See Table C attached).

The important physical and electrical properties of the various oilextended systems prepared in Examples .[.I-XII.]. .Iadd.I-XIII.Iaddend.are summarized in Table D. (See Table D attached).

Example I illustrates the understanding of the prior art thatpolyurethanes, being very polar elastomers are almost completelyincompatible with mineral oils. The results of this example reveals thata mineral oil cannot be used to obtain a compatible highly extendedpolyurethane (i.e., at least about 300% polymer extension) system in theabsence of couplers of the type described in this invention. Attempts toachieve high degrees of polyurethane extension with mineral oils andwithout a suitable coupler result in an incompatible system which spewsoil during and after cure and is accordingly unsuitable for reclamationof insulated electrical devices (.e.g, plastic insulated conductorcables, transformers, capacitors).

EXAMPLE I a. Prepolymer Formation

A reactor fitted with agitator, thermometer, nitrogen inlet and refluxcondenser was charged with 3120.0 grams (2.5 eq.) of a hydroxyl bearingpolybutadiene, 833.0 grams of 3-isocyanatomethyl, 3,5,5trimethylcyclohexyl isocyanate (7.5 eq.), 3953.0 grams of paraffin oiland 4.0 grams of benzoyl chloride. The solution was maintained at75°-85° C. for 5 hours under nitrogen. The free isocyanate content ofthe prepolymer was 2.56%.

b. Polymer Formation

25.0 grams (0.014 eq.) of the prepolymer was mixed with 16.8 grams(0.014 eq.) of a hydroxyl bearing polybutadiene, 57.8 grams of aparaffin oil and 0.4 grams of dibutyl in dilaurate.

                                      TABLE C                                     __________________________________________________________________________    Prepolymers                                                                                            Equivalent Wt.   Example Pre                         Polyol                                                                            Isocyanate                                                                            NCO/OH                                                                              % Free NCO                                                                           Per NCO Group                                                                          Viscosity (CPS)                                                                       polymer Used in                     __________________________________________________________________________    1   IPDI    3     2.56   1641     475     I, II, III, IV,                                                               XI                                  1   TDI     3     2.57   1635     330     V                                   3   TDI     2.47  10.8   389      20,000  VII, VIII, X, XII                   3   Polymeric MDI                                                                         5.14  7.2    584      150     XIII                                5   IPDI    3     4.85   866      4260    VI                                  6   IPDI    5     10.12  415.2    3850    IX                                  __________________________________________________________________________

                                      TABLE D                                     __________________________________________________________________________                              %           Dielectric                                                                          Volume Dissipation                       Coupler                                                                            %      %      Paraffin                                                                           % Polymer                                                                            Constant                                                                            Resistivity                                                                          Factor At                  Example No.                                                                          No.  Coupler/Wt.                                                                          Polymer/Wt.                                                                          Oil/Wt.                                                                            Extension                                                                            At 1KH.sub.z *                                                                      In OHM-cm*                                                                           1KH.sub.z *                __________________________________________________________________________    1 - Control                                                                          None 0      29.3   70.3 240    --    --     --                                                        (Incompatible                                                                 Spews Oil)                                     II     1    15.0   8.0    76.3 953    2.55  2.45 × 10.sup.13                                                               .009                       III    2    20.0   15.0   64.8 432    2.73  4.18 × 10.sup.12                                                               .011                       IV     3    20.0   15.0   64.0 427    3.01  1.33 × 10.sup.11                                                               .017                       V      4    25.0   8.0    66.8 835    2.68  1.36 × 10.sup.13                                                               .007                       VI     5    20.0   15.0   64.0 427    2.74  6.10 × 10.sup.11                                                               .017                       VII    6    24.8   12.4   61.4 495    3.29  1.53 × 10.sup.13                                                               .029                       VIII   7    24.8   12.4   61.6 497    2.74  2.59 ×0                                                                        .016up.10                  IX     1    20.0   15.0   64.0 427    2.71  3.47 × 10.sup.12                                                               .007                       X      13   20.0   15.0   64.5 430    2.99  6.89 × 10.sup.                                                                 .015                       XI     14   20.0   15.0   64.5 430    3.42  3.44 × 10.sup.10                                                               .025                       XII    15   20.0   15.0   64.5 430    3.23  1.07 × 10.sup.11                                                               .017                       XIII   .[.4.]..Iadd.6.Iaddend.                                                            30.0   35.0   35.0 100    3.0   2.43 × 10.sup.13                                                               .015                       __________________________________________________________________________     *Electrical measurements made at 25° C.                           

The resulting clear solution within 4 hours turned opaque and within 24hours cured at room temperature to greyish-white, opaque oil spewingmass containing 29.3% polymer which was incompatible with the 70.3%mineral oil.

EXAMPLE II a. Prepolymer Formation

Same prepolymer as in Example I.

b. Polymer Formation

6.4 grams (0.004 eq.) of the prepolymer was mixed with 4.8 grams (0.004eq.) of the hydroxyl bearing polybutadiene, 73.1 grams of mineral oil.15.0 grams of .[.2,2,4 trimethyl 1,3 pentanediol, diisobutyrate.]..Iadd.2,2,4 trimethyl 1,3 pentanediol diisobutyrate .Iaddend.and 0.7grams of dibutyl tin dilaurate. The resulting solution cured over a 120hour period to a clear, very soft, dry, non-oil spewing mass whichcontained 8% polymer and 76.3% mineral oil. This represents a 953%extension of the polymer by mineral oil.

EXAMPLE III a. Prepolymer Formation

Same as prepolymer as in Example I.

b. Polymer Formation

16.3 grams (0.01 eq.) of prepolymer was mixed with 1.5 grams (0.0045eq.) of castor oil, 5.3 grams (0.0045 eq.) of a hydroxyl bearingpolybutadiene, 56.6 grams of mineral oil, 20.0 grams of di-2-ethylhexylsebacate, and 0.3 grams of dibutyl tin dilaurate. The resulting solutioncured over a 48 hour period at room temperature to a clear, soft, dry,non-oil spewing mass containing 15% polymer and 64.8% mineral oil. Thisrepresents a 432% extension of the polymer with mineral oil.

EXAMPLE IV a. Prepolymer Formation

Same prepolymer as in Example I.

b. Polymer Formation

13.2 grams (0.0074 eq.) of prepolymer was mixed with 4.7 grams (0.0037eq.) of a hydroxyl bearing polybutadiene, 3.7 grams (0.0037 eq.) of apolypropylene glycol, 20.0 grams of acetyl tributyl citrate, 57.4 gramsof mineral oil and 1.0 grams of dibutyl tin dilaurate, The resultingsolution cured over a 48 hour period at room .[.temrature.]..Iadd.temperature .Iaddend.to a clear, soft, dry, non-oil spewing masscontaining 15% polymer and 64% mineral oil. This represents a 426%extension of the polymer with paraffin oil.

EXAMPLE V a. Prepolymer Formation

A reactor vessel equipped as in Example I was charged with 52.2 grams(0.6 eq.) of toluene diisocyanate (80/20), 181.3 grams of mineral oil,120.9 grams of di-2-ethylhexyl adipate, and 250.0 grams (0.2 eq.) of ahydroxyl bearing polybutadiene, and 0.3 grams of benzoyl chloride. Thesolution as heated under nitrogen for 4 hours at 75°-80° C. Theresulting prepolymer had a free isocyanate content of 2.57%.

b. Polymer Formation

6.3 grams of the prepolymer (0.039 eq.) was mixed with 4.8 grams (.0039eq.) of a hydroxyl bearing polybutadiene, 23.7 grams of di(2-ethylhexyl) adipate, 65.0 grams of mineral oil and 0.2 grams ofdibutyl tin dilaurate. The solution cured at room temperature over a 120hour period to a clear, very soft, dry, non-oil spewing mass containing8% polymer and 66.8% mineral oil. This represents an 835% extension ofthe polymer by mineral oil.

EXAMPLE VI a. Prepolymer Formation

A reactor equipped as in Example I was charged with 2487.0 grams (1.8eq.) of a triol (derived from the reaction of propylene oxide andtrimethylol propane) 600 grams of 3 isocyanatomethyl 3,5,5,trimethylcyclohexyl isocyanate (5.4 eq.), 1.6 grams of .[.benzoly.]..Iadd.benzoyl .Iaddend.chloride, and 1.6 grams of dibutyl tin dilaurate.The solution as heated at 80° C. for 6 hours under nitrogen. Theresulting prepolymer had a free isocyanate content of 4.85%.

b. Polymer Formation

6.4 grams (.0074 eq.) of the prepolymer, 8.6 grams of a hydroxyl bearingpolybutadiene (.0048 eq.), 20.0 grams of diisodecyl phthalate, 64.0grams of mineral oil and 1.0 grams of dibutyl tin dilaurate were mixed.The resulting solution cured at room temperature over a 48 hour periodto a clear, soft, dry, non-oil spewing mass containing 15% polymer and64% mineral oil. This represents a 427% mineral oil extension of thepolymer.

EXAMPLE VII a. Prepolymer Formation

A reaction vessel equipped as in Example I as well as with a droppingfunnel, was charged with 386.0 grams (4.44 eq.) of toluene diisocyanate614.0 grams of castor oil (1.8 eq.) was added, over a 2 hour period,through the dropping funnel at 70°-80° C. After the addition wascomplete, the reactor was held at 75° C. for 1 hour. The free isocyanatecontent of the prepolymer was 10.8%.

b. Polymer Formation

3 grams (.0076 eq.) of the prepolymer was mixed with 9.4 grams (.0076eq.) of a hydroxy bearing polybutadiene, 24.8 grams of dioctyl adipate,61.4 grams of paraffin oil and 1.4 grams of dibutyl tin dilaurate. Theresulting solution cured at room temperature over a 48 hour period to asoft, clear, dry, non-oil spewing mass which contained 12.4% polymer and71.4% mineral oil. This represents a 495% extension of the polyurethanewith mineral oil.

EXAMPLE VIII a. Prepolymer Formation

Same prepolymer as in Example VII.

b. Polymer Formation

2.4 grams (.0061 eq.) of the prepolymer was mixed with 10.0 grams of ahydroxyl bearing copolymer of styrenebutadiene (.0061 eq.), 24.8 gramsof tributyl phosphate, .[.61.4.]. .Iadd.61.6 .Iaddend.grams of mineraloil and 1.2 grams of dibutyl tin dilaurate. The resulting solution curedat room temperature over a 48 hour period to a soft, clear, dry, non-oilspewing mass containing 12.4% polymer and 61.6% mineral oil. Thisrepresents a 497% mineral oil extension of the polyurethane.

EXAMPLE IX a. Prepolymer Formation

A reactor fitted with agitator, thermometer nitrogen inlet and refluxcondenser was charged with 1001.8 grams (1 eq.) of a.[.polytetramethylene glycol.]. .Iadd.polytetramethylene ether glycol.Iaddend.and 555.5 grams (5 eq.) of .[.3-isocyanatomenthyl,.]..Iadd.3-isocyanatomethyl, .Iaddend.3,5,5 trimethylcyclohexyl isocyanate.The solution was maintained at 80° C. for 2 hours. The resultingprepolymer had a free isocyanate content of 10.12%.

b. Polymer Formation

3.7 grams (.0089 eq.) of the prepolymer was mixed with 11.3 grams (.0089eq.) of a hydroxyl bearing polybutadiene (OH functionality 2.3-2.4) 64.0grams of a mineral oil, 20.0 grams of 2,2,4 trimethyl--1,3 pentanedioldiisobutyrate and 1.0 grams of dibutyl tin dilaurate. The resultingsolution cured after 11/2 hours at 100° C. to a clear, dry, non-oilspewing mass containing 15% polymer and 64% mineral oil. This representsa 427% mineral oil extension of the polymer.

EXAMPLE X a. Prepolymer Formation

Same prepolymer as in Example VII.

b. Polymer Formation

3.5 grams (0.009 eq.) of the prepolymer was mixed with 11.5 grams (.009)of hydroxy bearing polybutadiene, 20.0 grams of isobutyl acetate, 64.5grams of a mineral oil and 0.5 grams of dibutyl tin dilaurate. Theresulting solution cured over a 24 hour period at room temperature.[.of.]. .Iadd.to .Iaddend.a soft, clear, dry, non-oil spewing masswhich contained 15% polymer and 64.5% mineral oil. This was a 430%mineral oil extension of the polymer.

EXAMPLE XI a. Prepolymer Formation

Same Prepolymer as in Example I.

b. Polymer Formation

12.5 grams of prepolymer (0.0077 eq.) was mixed with 8.8 grams (0.0077eq.) of a hydroxyl bearing polybutadiene, 20.0 grams of methyl-ethylketone, 58.2 grams of mineral oil and 0.5 grams of dibutyl tindilaurate. The resulting solution cured at room temperature over a 48hour period to a soft, dry, non-oil spewing mass containing 15% polymerand 64.5 percent mineral oil. This represents a 430% extension of thepolymer by mineral oil.

EXAMPLE XII a. Prepolymer Formation

Same prepolymer as in Example VII.

b. Polymer Formation

3.5 grams (.009 eq.) of prepolymer was mixed with 11.5 grams (.009 eq.)of a hydroxyl bearing polybutadiene, 20.0 grams of methyl-n-butylketone, 64.5 grams of mineral oil and 0.5 grams of dibutyl tindilaurate. The resulting solution cured at room temperature over a 24hour period .[.of.]. .Iadd.to .Iaddend.a clear, soft, dry, non-oilspewing mass which contained 15% polymer and 64.5% mineral oil. This wasa 430% mineral oil extension of the polymer.

EXAMPLE XIII a. Prepolymer Formation

A reactor vessel equipped as in Example I was charged with 145 grams(0.42 eq.) of castor oil, 286 grams polymeric MDI (2.16 eq.) and 569grams dioctyl adipate (DOA) the solution was heated under nitrogen for 2hours at 60° C. The resulting prepolymer had a free isocyanate contentof 7.2%.

b. Polymer Formation

17.0 grams of the prepolymer (0.03 eq) were mixed with 26.2 grams (0.021eq) of a hydroxyl bearing polybutadiene, 1.4 grams castor oil (0.004 eq)35 grams of mineral oil, 20.1 grams of DOA and 0.3 grams dibutyl tindilaurate. The solution cured at room temperature over a 24 hour periodto a clear, firm, dry, non-oil spewing elastomeric material containing35 percent polymer and 35 percent mineral oil. This represents a 100percent exension of the polymer by mineral oil.

In the preceding examples the hydroxyl terminated liquid homopolymer ofpolybutadiene employed is available from the Altantic-Richfield Co.under the trade name POLY-BD R-45HT. Its typical properties are:

    ______________________________________                                        Polybutadiene                                                                 isomer content                                                                              Viscosity at 75° F. - 80 poise                           Trans 1,4 - 60%                                                                             Moisture weight percent - 0.05                                   Cis 1,4 - 20%                                                                              Iodine No. 398                                                  Vinyl 1,2 - 20%                                                                             Hydroxyl content - 0.85 Meg/GM                                  ______________________________________                                    

The mineral oil used in the examples is available from Pennrico Inc.,Butler, Pennsylvania as "PENETECK", a highly paraffinic white oil.

The materials produced in Examples I-XIII had an initial (low) viscosityon the order of about 0.1 poises. However, within about 1 to 120 hoursthe material cured in situ at temperatures from about 15° C. to about100° C. to a gel-like (high) viscosity on the order of between 1,000 and100,000 .[.poises..]. .Iadd.centipoise. .Iaddend.The mineral oil wascompletely compatible with the prepolymer and polyol in all of ExamplesII-XIII. In each case the mineral oil did not interfere with thereaction of the prepolymer and polyol constituents to form apolyurethane compound which cured to a gel. In each instance the mineralextender oil did not exude or spew from the cured urethane system.

The elastomeric rehabilitation materials of this invention are ideallysuited for use in reclaiming waterlogged electrical apparatus such as,for example, plastic insulated conductors of the type employed inmulti-pair telephone cables. The method of employing these mineral oilextended urethanes in rehabilitating such an apparatus will now beillustrated with reference to FIG. 1.

In the cable illustrated in FIG. 1, a plurality of wire conductors 1 aredisposed within the central core 2 of the cable. Each wire is surroundedby an insulating material, generally a polyolefin plastic. The pluralityof insulated wires are tightly enclosed within a spiral wound sheath 3,usually a polyethylene terephthalate sheet material. Surrounding thesheath are two protective shields 4, made of a flexible metal sheetingsuch as aluminum. The shields are separated from one another by acontinuous layer 5 of a suitable insulating material. Finally, an outerjacket 6 of a protective plastic such as polyethylene, covers theoutermost aluminum layer and serves to protect the cable.

Aqueous contaminants generally find their way into the cable throughpinholes and stress cracks that develop around fittings and cableconnectors, ultimately lodging in the interior free spaces of centralcore 2. After a particular aqueous contaminant, for example water, hasbeen present for some time in the core, the electrical properties of thecable can be deleteriously effected as previously described. At thispoint, the rehabilitation products and processes of this invention maybe employed to restore the cable to substantially its original operatingcondition.

The rehabilitation operation is carried out on location by firstadmixing approximately equal .[.amount.]. .Iadd.amounts .Iaddend.of theprepolymer and polyol ingredients which are most advantageously preparedin advance. A small portion of the cable outer protective layersincluding jacket 6, aluminum protective shields 4 and sheath 3 are thenremoved and a nipple (not shown) installed in the opening thus formed,using techniques that are well-known in the trade. This operation can becarried out from above, or below, and without removing the cable fromits resting place. The mineral oil extended polyurethane elastomerhaving just been formed has a relatively low viscosity and is easilyintroduced into the core of the cable through a hose (not shown)connected to the nipple. After the rehabilitation material has beeninjected into the cable, the delivery hose is withdrawn from the nippleand the hole in the nipple is sealed with a plug (not shown). Theinjection operation will have driven the low viscosity mineral extendedurethane out through the interior-free spaces of the cable. Therehabilitation agent will displace the water penetrants in the interiorfree spaces (e.g. between the individual wires and the outerpolyethylene terephthalate sheath).

In the practice of the invention, the viscosity of the rehabilitationmaterial at from about 15° C. to about 50° C. at the time of injectionshould be within the range of about 10 to 100 centipoises. Withinseveral hours after injection into an insulated electrical device, therehabilitation agent cures to form an oil extended polymer system havinga gel-like consistency and a viscosity on the order of about 1000.[.poises..]. .Iadd.centipoise. .Iaddend.The clear gel is physically andchemically stable and does not lose mineral oil by exudation or spewing.The hydrophobic nature of the cured oil extended elatomer system alsoserves to seal the cable against subsequent penetration of water orother fluid materials. Furthermore, the gelled system has goodinsulating properties due to its relatively low dielectric constant andhigh volume resistivity.

The elastomer material retains the mineral oil and no exudation wasevident in any of the formulations made in Examples II-.[.XII.]..Iadd.XIII .Iaddend.after standing for several weeks at ambient (room)temperature. Moreover, the mineral oil extended urethanes were found tobe compatible with the polycarbonate plastic connectors used in theinterconnection of insulated electrical devices. After several weeksexposure to the rehabilitation compounds of this invention, thepolycarbonate connectors on plastic insulated conductor cable werecompletely unaffected and did not exhibit any signs of chemical attack.The rehabilitation compounds were also compatible with polyolefininsulating materials used in the cable manufacture and no stresscracking was observed after several weeks exposure.

The oil extended rehabilitation material was non-solvating in nature anddid not attack polyethylene terephthalate or the other polymer materialsemployed in the cable construction. The material was also characterizedby easy handling in view of its low volatility (vapor pressure) andinoffensive aroma. No toxicity or adverse side effects have been notedby those handling the rehabilitation materials of this invention, thussetting them apart from the relatively toxic products previouslyemployed in reclamation techniques.

The treated cable showed only a minor weight gain, which is probablyattributable to the low density of the cured rehabilitation material. Ithas also been noted that the present system results in only a minimalamount of air being entrapped in the cured system after injection intoan insulated electrical device. This can be related to the low viscosityand density of the initial ingredients which may be pumped into thecable without causing excessive turbulence.

In addition to the reclamation of insulated electrical apparatus, themineral oil polymer system can also be used as a waterproofing membranein the construction field, cast into a resilient flooring compound(using higher level of polymer as represented by Example XIII); used asa liquid casting system for a variety of potting and encapsulationapplications as well as a solid lubricant to replace grease in certainsituations.

While this invention has been described and illustrated by the examplesshown, it is not intended to be strictly limited thereto, and othervariations and modifications may be employed within the scope of thefollowing claims.

We claim:
 1. A .Iadd.cured, cross-linked, .Iaddend.mineral oil extendedpolyurethane .[.system.]. comprising the reaction product of anisocyanate terminated prepolymer with a polyol .Iadd.selected from thegroup consisting of castor oil, polyether polyols, hydroxyl bearinghomopolymers of butadiene, hydroxyl bearing copolymers of butadiene andstyrene, and combinations thereof, .Iaddend.in the presence of a mineral.Iadd.oil .Iaddend.and a liquid coupling agent for compatibilizing saidmineral oil with said polyurethane, said .Iadd.mineral oil extended.Iaddend.polyurethane .[.system.]. containing from about 8 to about 20parts of .[.said urethane polymer.]. .Iadd.polyurethane.Iaddend., fromabout 60 to about 75 parts mineral oil and from about 10 to about 25parts of .[.coupler.]. .Iadd.coupling agent.Iaddend., all partsexpressed on a weight basis, said liquid coupling agent being misciblein all proportions with said mineral oil, said coupling agent.Iadd.being .Iaddend.selected from the group consisting of a ketone andan ester .[.of an organic compound selected from the group consisting ofa diol and a diacid.]., said agent having a boiling temperature above220° F., a solubility parameter between 7.0 and 9.5 and a hydrogenbonding index number in the range from .[.8.2 to 8.8.]. .Iadd.6.0 to12.0, and said agent being non-reactive with the prepolymer and thepolyol.Iaddend., said isocyanate terminated prepolymer .Iadd.beingprepared by reacting a polyisocyanate .Iaddend.selected from the groupconsisting of cycloaliphatic diisocyanate, aliphatic diisocyanate andaromatic diisocyanate .[.; said.]. .Iadd.with a .Iaddend.polyol selectedfrom the group consisting of castor oil.Iadd., .Iaddend..[.and.].polyether .Iadd.polyols, hydroxyl bearing homopolymers of butadiene,hydroxy bearing copolymers of butadiene and styrene, and combinationsthereof .Iaddend.wherein at least .[.one of said urethane formingreactants include a hydroxy bearing polybutadiene constituent.]. .Iadd.aportion of the polyol used in the preparation of the polyurethane isselected from the group consisting of hydroxyl bearing homopolymers ofbutadiene and hydroxyl bearing copolymers of butadiene andstyrene.Iaddend., the mineral oil extended polyurethane when curedretaining the mineral oil within its structure, thereby preventing theoil from spewing and exuding from said cured composition.[., saidcomposition possessing a gel-like consistency.]..
 2. .[.Productaccording to.]. .Iadd.The cured, cross-linked, mineral oil extendedpolyurethane of .Iaddend.claim 1 in which the mineral oil employed isparaffin oil.
 3. .[.Product according to.]. .Iadd.The cured,cross-linked, mineral oil extended polyurethane of .Iaddend.claim 1 inwhich the liquid coupling agent is 2,2,4-trimethyl.Badd..[.1,1,3-pentane diol.]..Baddend. .Iadd.1,3 pentanediol.Iaddend.diisobutyrate.
 4. .[.Product according to.]. .Iadd.The cured,cross-linked, mineral oil extended polyurethane of .Iaddend.claim 1 inwhich the coupling agent is di-2 ethyl hexyl adipate.
 5. .[.Productaccording to.]. .Iadd.The cured, cross-linked, mineral oil extendedpolyurethane of .Iaddend.claim 1 wherein said isocyanate terminatedprepolymer is the reaction product of.Badd..[.3-isocyanatoemethyl.]..Baddend. .Iadd.3-isocyanato-methyl.Iaddend.3,3,5-trimethylcyclohexyl isocyanate and a liquid hydroxylterminated homopolymer of butadiene.
 6. A .Iadd.cured, cross-linked,.Iaddend.mineral oil extended polyurethane .[.system.]. comprising thereaction product of an isocyanate terminated prepolymer with a polyol.Iadd.selected from the group consisting of castor oil, polyetherpolyols, hydroxyl bearing homopolymers of butadiene, hydroxyl bearingcopolymers of butadiene and styrene, and combinations thereof,.Iaddend.in the presence of a mineral oil and a liquid coupling agentfor compatibilizing said mineral oil with said polyurethane, said.Iadd.mineral oil .Iaddend.extended polyurethane .[.system.]. containingfrom about 8 to .Iadd.about .Iaddend.45 parts of polyurethane .[.saidurethane polymer.]., from about 25 to about 75 parts mineral oil andfrom about 10 to about 35 parts of .[.coupler.]. .Iadd.couplingagent.Iaddend., all parts expressed on a weight basis, said liquidcoupling agent being miscible in all proportions with said mineral oil,said coupling agent selected from the group .[.consiting.]..Iadd.consisting .Iaddend.of a ketone and an ester .[.of an organiccompound selected from the group consisting of a diol and a diacid.].,said agent having a boiling temperature above 220° F., a solubilityparameter between 7.0 and 9.5 and a hydrogen bonding index number in therange from .Badd..[.8.2 to 8.8.]..Baddend., .Iadd.6.0 to 12.0 and saidagent being non-reactive with the prepolymer and the polyol,.Iaddend.said isocyanate terminated prepolymer .Iadd.being prepared byreacting a polyisocyanate selected from the group consisting ofcycloaliphatic diisocyanate, aliphatic diisocyanate and aromaticdiisocyanate with a polyol .Iaddend.selected from the group consistingof castor oil .[.and.]..Iadd., .Iaddend.polyether .Iadd.polyols,hydroxyl bearing homopolymers of butadiene, hydroxyl bearing copolymersof butadiene and styrene, and combinations thereof, .Iaddend.wherein atleast .[.one of said urethane forming reactants include a hydroxybearing polybutadiene constituent.]. .Iadd.a portion of the polyol usedin the preparation of the polyurethane is selected from the groupconsisting of hydroxyl bearing homopolymers of butadiene and hydroxylbearing copolymers of butadiene and styrene.Iaddend., the mineral oilextended polyurethane when cured retaining the mineral oil within itsstructure, thereby preventing the oil from spewing and exuding from saidcured composition.[., said composition possessing a gel-likeconsistency.]..
 7. A .Iadd.cured, cross-linked, .Iaddend.mineral oilextended polyurethane .[.system.]. comprising the reaction product of anisocyanate terminated prepolymer with a polyol .Iadd.selected from thegroup consisting of castor oil, polyether polyols, hydroxyl bearinghomopolymers of butadiene, hydroxyl bearing copolymers of butadiene andstyrene, and combinations thereof, .Iaddend.in the presence of a mineraloil and a liquid coupling agent for compatabilizing said mineral oilwith said polyurethane, said .Iadd.mineral oil extended.Iaddend.polyurethane .[.system.]. containing from about 20 to about 45parts of .[.said urethane polymer.]. .Iadd.polyurethane.Iaddend., fromabout 25 to about 60 parts mineral oil and from about 25 to about 35parts of .[.coupler.]. .Iadd.coupling agent.Iaddend., all partsexpressed on a weight basis, said liquid coupling agent being misciblein all proportions with said mineral oil, said coupling agent.Iadd.being .Iaddend.selected from the group consisting of a ketone andan ester .[.of an organic compound selected from the group consisting ofa diol and diacid.]., said agent having a boiling temperature above 220°F., a solubility parameter between 7.0 and 9.5 and a hydrogen bondingindex number in the range from .Badd..[.8.2 to 8.8.]., .Iadd.6.0 to 12.0and said agent being non-reactive with the prepolymer and the polyol,.Iaddend.said isocyanate terminated prepolymer .Iadd.being prepared byreacting a polyisocyanate .Iaddend.selected from the group consisting ofcycloaliphatic diisocyanate, aliphatic diisocyanate and aromaticdiisocyanate.[.; said.]. .Iadd.with a .Iaddend.polyol selected from thegroup consisting of castor oil .[.and.]..Iadd., .Iaddend.polyether.Iadd.polyols, hydroxyl bearing homopolymers of butadiene, hydroxylbearing copolymers of butadiene and styrene, and combinations thereof,.Iaddend.wherein at least .[.one of said urethane forming reactantsinclude a hydroxy bearing polybutadiene constituent.]. .Iadd.a portionof the polyol used in the preparation of the polyurethane is selectedfrom the group consisting of hydroxyl bearing homopolymers of butadieneand hydroxyl bearing copolymers of butadiene and styrene.Iaddend., themineral oil extended polyurethane when cured retaining the mineral oilwithin its structure, thereby preventing the oil from spewing andexuding from said cured composition.[., said composition being useful asa casting system.]..
 8. .[.Composition according to.]. .Iadd.The cured,cross-linked, mineral oil extended polyurethane of .Iaddend.claim 1which .[.preferably contains.]. .Iadd.comprises from .Iaddend.about121/2 to about 15 parts by weight of .[.said urethane polymer.]..Iadd.polyurethane, from .Iaddend.about 65 to about 70 parts .Iadd.byweight .Iaddend.of mineral oil and from about 15 to about 20 parts byweight of .[.coupler.]. .Iadd.coupling agent.Iaddend.. .Iadd.
 9. Thecured, cross-linked, mineral oil extended polyurethane of claim 1wherein said coupling agent has a hydrogen bonding index number in therange from 8.2 to 8.8. .Iaddend. .Iadd.10. The cured, cross-linked,mineral oil extended polyurethane of claim 6 wherein said coupling agenthas a hydrogen bonding index number in the range from 8.2 to 8.8..Iaddend. .Iadd.11. The cured, cross-linked, mineral oil extendedpolyurethane of claim 7 wherein said coupling agent has a hydrogenbonding index number in the range from 8.2 to 8.8. .Iaddend. .Iadd.12. Acured, cross-linked, mineral oil extended polyurethane which isnon-spewing comprising:(a) from about 8 to about 45 parts, by weight, ofpolyurethane, said polyurethane being prepared by reacting(i) apolyisocyanate prepolymer prepared by the reaction of a polyisocyanatewith a polyol selected from the group consisting of castor oil,polyether polyols, hydroxyl bearing homopolymers of butadiene, hydroxylbearing copolymers of butadiene, and combinations thereof, with (ii) apolyol selected from the group consisting of castor oil, polyetherpolyols, hydroxyl bearing homopolymers of butadiene, hydroxyl bearingcopolymers of butadiene, and combinations thereof; (b) from about 25 toabout 75 parts, by weight, of mineral oil, (c) from about 10 to about 35parts, by weight, of coupling agent, said coupling agent beingcharacterized by(i) being miscible in all proportions with said mineraloil, (ii) having a solubility parameter between 7.0 and 9.5, (iii)having a hydrogen bonding index number in the range of from 6.0 to 12.0,and (iv) being non-reactive with the prepolymer and the polyol,andwherein the cured, cross-linked polyurethane is characterized by thepresence of a polybutadiene moiety in the polyurethane structure..Iaddend. .Iadd.13. The cured, cross-linked, mineral oil extendedpolyurethane of claim 12 wherein said coupling agent is selected fromthe group consisting of a ketone and an ester. .Iaddend. .Iadd.14. Thecured, cross-linked, mineral oil extended polyurethane of claim 13wherein said polyisocyanate is selected from the group consisting ofcycloaliphatic diisocyanate, aliphatic diisocyanate and aromaticdiisocyanate. .Iaddend. .Iadd.15. The cured, cross-linked, mineral oilextended polyurethane of claim 14 wherein said coupling agent is furthercharacterized by having a boiling temperature above 220° F. .Iaddend..Iadd.16. The cured, cross-linked, mineral oil extended polyurethane ofclaim 15 wherein said coupling agent has a hydrogen bonding index numberin the range of from 8.2 to 8.8. .Iaddend. .Iadd.17. The cured,cross-linked, mineral oil extended polyurethane of claim 15 wherein oneof the polyols of claim 12(a)(i) and (a)(ii) is castor oil. .Iaddend..Iadd.18. The cured, cross-linked, mineral oil extended polyurethane ofclaim 15 wherein the polyols of claim 12(a)(i) and (a)(ii) are selectedfrom the group consisting of hydroxyl bearing homopolymers of butadiene,hydroxyl bearing copolymers of butadiene and styrene, and combinationsthereof. .Iaddend. .Iadd.19. The cured, cross-linked, mineral oilextended polyurethane of claim 15 wherein said mineral oil is a paraffinoil. .Iaddend. .Iadd.20. The cured, cross-linked, mineral oil extendedpolyurethane of claim 15 which comprises from about 8 to about 20 partsof polyurethane, from about 60 to about 75 parts of mineral oil and fromabout 10 to about 25 parts of coupling agent, all parts expressed on aweight basis. .Iaddend. .Iadd. The cured, cross-linked, mineral oilextended polyurethane of claim 15 which comprises from about 20 to about45 parts of polyurethane, from about 25 to about 60 parts of mineral oiland from about 25 to about 35 parts of coupling agent, all partsexpressed on a weight basis. .Iaddend. .Iadd.22. The cured,cross-linked, mineral oil extended polyurethane of claim 15 whichcomprises from about 121/2 to about 15 parts of polyurethane, from about65 to about 70 parts of mineral oil and from about 15 to about 20 partsof coupling agent, all parts expressed on a weight basis. .Iaddend..Iadd.23. A cured, cross-linked, mineral oil extended polyurethane whichis non-spewing comprising from about 8 to about 45 parts ofpolyurethane, from about 25 to about 75 parts of mineral oil and fromabout 10 to about 35 parts of coupling agent, all parts expressed on aweight basis, wherein the cured, cross-linked polyurethane ischaracterized by the presence of a polybutadiene moiety in thepolyurethane structure and is prepared from a mineral oil extendedpolyurethane precursor in admixture with the coupling agent, saidcoupling agent being characterized by:(a) possessing a solubilityparameter between 7.0 and 9.5; (b) having a hydrogen bonding indexnumber in the range of 6.0 to 12.0; (c) being miscible in allproportions with said mineral oil; and (d) being non-reactive with saidpolyurethane precursor. .Iaddend. .Iadd. The cured, cross-linked,mineral oil extended polyurethane of claim 23 wherein the polybutadienemoiety is derived from at least one member of the group consisting ofhydroxyl bearing homopolymers of butadiene and hydroxyl bearingcopolymers of butadiene and styrene. .Iaddend. .Iadd.25. The cured,cross-linked, mineral oil extended polyurethane of claim 24 wherein saidcoupling agent is further characterized by having a boiling temperatureabove 220° F. .Iaddend.